Background: Lichen sclerosus (LS) of the vulva in children is presenting more commonly, but its origin is unknown. Objective: The purpose of this study was to assess the prevalence of childhood vulvar LS, to examine factors that may play a role in its cause, and to attempt to define the current optimal treatment. Methods: We surveyed 70 cases of LS currently being treated in the pediatric vulvar clinic to collect information on presentation, family history, associated disease, and typical course of the disorder. We looked retrospectively and prospectively at treatments for LS. Results: We found a prevalence of premenarchal LS of 1 in 900 and confirmed an increasing incidence. In a high proportion of cases (77%), the question of sexual abuse had been raised. A family history of LS was found in a minimum of 17% of cases. Associated autoimmune disease occurred in 14%, but 64% told of a family history, and atopy occurred in 59%. Potent topical steroid ointments appear to alleviate symptoms most effectively, with minimal side effects. Conclusion: Although the cause of LS remains uncertain, it is not a rare disease in prepubertal girls. Current optimal management includes prompt diagnosis and institution of treatment with a potent topical steroid. (J Am Acad Dermatol 2001;44:803-6.)